This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A222771 #6 Jul 23 2025 03:02:54 %S A222771 0,4,13,66,158,934,2446,14567,39972,240130,673665,4073862,11545686, %T A222771 70212506,200446066,1224207384,3512430906,21526789216,62001340484, %U A222771 381049009426,1100824791540,6780941436208,19637801359798,121196222602133 %N A222771 Number of 3Xn 0..1 arrays with exactly floor(3Xn/2) elements unequal to at least one horizontal or antidiagonal neighbor, with new values introduced in row major 0..1 order. %C A222771 Row 3 of A222769 %H A222771 R. H. Hardin, <a href="/A222771/b222771.txt">Table of n, a(n) for n = 1..48</a> %e A222771 Some solutions for n=3 %e A222771 ..0..0..0....0..0..0....0..1..0....0..1..1....0..0..1....0..0..0....0..0..0 %e A222771 ..0..0..0....0..0..0....0..0..0....0..1..1....1..0..0....0..0..1....0..0..1 %e A222771 ..0..1..0....1..1..1....0..0..0....1..1..1....0..0..0....1..0..0....0..0..1 %K A222771 nonn %O A222771 1,2 %A A222771 _R. H. Hardin_ Mar 05 2013